Field devices are often put into operation and maintained in a computer-assisted manner. For example, a connection to a laptop or PC is produced either directly, for example by a USB interface or via a communications adapter, in order to carry out parameterisations and/or diagnostics via this connection by means of an interface at the field device which can be a level measuring device, a limit detection device, a pressure measuring device or a flow measuring device.
In the following, a laptop or PC of this type will also be called a control unit or an operator device. This is quite generally an arithmetic-logic unit which can communicate with the field device via an appropriate data connection in order to carry out a parameterisation or to read out diagnostic data or measured data in the field device.
In many cases, there is a considerable amount of data to be exchanged between the control unit and the field device.